Inopin Mechanism of Action

Pharmacology: Pharmacodynamics: Dopamine stimulates both adrenergic and dopaminergic receptors, lower doses are mainly dopaminergic stimulating and produce renal and mesenteric vasodilation, higher doses also are both dopaminergic and beta₁-adrenergic stimulating and produce cardiac stimulation and renal vasodilation; large doses stimulate alpha-adrenergic receptors.
Pharmacokinetics: Following IV administration, the onset of action of Dopamine occurs within 5 minutes, and the drug has a duration of action of less than 10 minutes. Dopamine is widely distributed in the body but does not cross the blood-brain barrier to a substantial extent. Dopamine has a plasma half-life of about 2 minutes. Dopamine is metabolized in the liver, kidneys, and plasma by monoamineoxidase (MAO) and catechol-O-methyltransferase to the inactive compounds homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid. In patients receiving MAO inhibitors, the duration of action of Dopamine may be as long as 1 hour. About 25% of a dose of Dopamine is metabolized to norepinephrine within the adrenergic nerve terminals. Dopamine is excreted in urine principally as HVA and its sulfate and glucuronide conjugates and 3,4-dihydroxyphenylacetic acid. A very small fraction of a dose is excreted unchanged. Following administration of radiolabeled Dopamine, approximately 80% of the radioactivity reportedly is excreted in urine within 24 hours.
Pediatric: The reported clearance rate of Dopamine in critically ill infants and children has ranged from 46 to 168 mL/kg/min, with the higher values seen in the younger patients. The apparent volume of distribution in neonates is reported as 0.6 to 4 L/kg, leading to an elimination half-life of 5 to 11 minutes.